How to Calculate Cousin Relationships
"Second cousin twice removed" sounds like a puzzle, but there's a simple logic behind every cousin label. Once you learn the two rules, you can work out any relationship.
Cousin relationships confuse almost everyone, yet they follow a precise, learnable system. Two numbers do all the work: the degree (first, second, third) and the remove. Master those and no family relationship will stump you again.
Start with the shared ancestor
Every cousin relationship is defined by a common ancestor. First cousins share a grandparent; second cousins share a great-grandparent; third cousins share a great-great-grandparent. The first step in figuring out any cousin relationship is to find the most recent ancestor the two people have in common.
Build your family tree — free
Kinidhi's tree maker lets you add relatives in a few taps, with the correct kinship term computed for every relative. No sign-up, nothing leaves your device, and you can download the finished tree as an image.
Open the free tree maker →The 'degree' rule
Count the generations from the shared ancestor down to the closer of the two people. If the nearest common ancestor is that person's grandparent (2 generations), they're first cousins; great-grandparent (3 generations), second cousins; and so on. The degree is always one less than the number of generations back — grandparent (2 gens) gives first cousins.
The 'removed' rule
"Removed" measures a generation gap between the two cousins. If both are the same number of generations from the shared ancestor, no remove applies. If one is a generation closer, they are "once removed"; two generations, "twice removed." Your parent's first cousin is your first cousin once removed.
Worked examples
You and the child of your first cousin share your grandparents. You're 2 generations down; they're 3. Same-degree count uses the closer person (you, first cousins), plus a one-generation gap — so they're your first cousin once removed. You and someone who shares your great-grandparents, both equally far down, are second cousins.
Build your family tree — free
Kinidhi's tree maker lets you add relatives in a few taps, with the correct kinship term computed for every relative. No sign-up, nothing leaves your device, and you can download the finished tree as an image.
Open the free tree maker →Why it matters in Indian families
In many Indian languages, these English cousin categories don't map neatly — cross and parallel cousins have entirely separate terms, and some are traditionally treated as siblings. Understanding both the English system and your own language's terms lets you record relationships precisely in your family tree.
Frequently asked questions
What does 'once removed' mean?
It means there is a one-generation gap between the two cousins. Your first cousin once removed is either your parent's first cousin or your first cousin's child — one generation away from you.
How do I know if someone is a second or third cousin?
Find your most recent shared ancestor. If it's a great-grandparent, you're second cousins; a great-great-grandparent makes you third cousins. Each further generation adds one to the cousin number.